Method and apparatus for providing station to station uniformity

ABSTRACT

An apparatus for processing stacks is provided. A first gas source is provided. A first gas manifold is connected to the first gas source. A first processing station has a first gas outlet, wherein the first gas outlet is connected to the first gas manifold. A first variable conductance valve is between the first gas source and the first gas outlet along the first gas manifold.

CROSS REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. application Ser. No. 16/115,970filed on Aug. 29, 2018, the entire content of which is incorporatedherein by reference thereto.

BACKGROUND

The present disclosure relates to the formation of semiconductordevices. More specifically, the disclosure relates to the formation ofsemiconductor devices in a system where a multiple stations share a gassource.

SUMMARY

To achieve the foregoing and in accordance with the purpose of thepresent disclosure, an apparatus for processing substrates is provided.A first gas source is provided. A first gas manifold is connected to thefirst gas source. A second gas manifold is connected to the first gassource. A first processing station has a first gas outlet, wherein thefirst gas outlet is connected to the first gas manifold. A secondprocessing station has a second gas outlet, wherein the second gasoutlet is connected to the second gas manifold. A first variableconductance valve is between the first gas source and the first gasoutlet along the first gas manifold. A second variable conductance valveis between the first gas source and the second gas outlet along thesecond gas manifold.

In another manifestation, an apparatus for processing stacks isprovided. A first gas source is provided. A first gas manifold isconnected to the first gas source. A first processing station has afirst gas outlet, wherein the first gas outlet is connected to the firstgas manifold. A first variable conductance valve is between the firstgas source and the first gas outlet along the first gas manifold.

In another manifestation, a method of processing a plurality of stacks,in a processing system comprising first gas source, a first gas manifoldconnected to the first gas source, a second gas manifold connected tothe first gas source, a first processing station with a first gasoutlet, wherein the first gas outlet is connected to the first gasmanifold, a second processing station with a second gas outlet, whereinthe second gas outlet is connected to the second gas manifold, a firstvariable conductance valve between the first gas source and the firstgas outlet along the first gas manifold, a second variable conductancevalve between the first gas source and the second gas outlet along thesecond gas manifold, a first mixing manifold between the first gasmanifold and the first gas outlet, wherein the first variableconductance valve is between the first gas source and the first mixingmanifold, a second mixing manifold between the second gas manifold andthe second gas outlet, wherein the second variable conductance valve isbetween the first gas source and the second mixing manifold, a secondgas source, a third gas manifold connected between the second gas sourceand the first mixing manifold, a fourth gas manifold connected betweenthe second gas source and the second mixing manifold, a third variableconductance valve connected between second gas source and the firstmixing manifold along the third gas manifold, a fourth variableconductance valve connected between the second gas source and the secondmixing manifold along the fourth gas manifold, a fifth variableconductance valve between the first mixing manifold and the first gasoutlet, and a sixth variable conductance valve between the second mixingmanifold and the second gas outlet, the method comprising adjusting thefirst variable conductance valve, the second variable conductance valve,the third variable conductance valve, the fourth variable conductancevalve, the fifth variable conductance valve, and the sixth variableconductance valve to provide improved uniformity between the firstprocessing station and the second processing station.

These and other features of the present disclosure will be described inmore detail below in the detailed description of the disclosure and inconjunction with the following figures.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is illustrated by way of example, and not by wayof limitation, in the figures of the accompanying drawings and in whichlike reference numerals refer to similar elements and in which:

FIG. 1 is a schematic illustration of an embodiment.

FIG. 2 is a schematic view of a process chamber that may be used in anembodiment.

FIG. 3 is a schematic view of a computer system that may be used inpracticing an embodiment.

FIG. 4 is a flow chart of an embodiment.

FIG. 5A is a top cut away view of another embodiment.

FIG. 5B is a cut away side view of the embodiment shown in FIG. 5A.

FIG. 6 is a schematic illustration of a gas system used in theembodiment shown in FIG. 5A.

DETAILED DESCRIPTION

The present disclosure will now be described in detail with reference toa few preferred embodiments thereof as illustrated in the accompanyingdrawings. In the following description, numerous specific details areset forth in order to provide a thorough understanding of the presentdisclosure. It will be apparent, however, to one skilled in the art,that the present disclosure may be practiced without some or all ofthese specific details. In other instances, well known process stepsand/or structures have not been described in detail in order to notunnecessarily obscure the present disclosure.

FIG. 1 is a schematic illustration of an embodiment. In this example, asystem is provided with a first gas source 104 and a second gas source108. The first gas source 104 is connected to a first variableconductance valve 112 and a second variable conductance valve 116. Avariable conductance valve is a valve that provides an adjustable flowresistance. The second gas source 108 is connected to a third variableconductance valve 120 and a fourth variable conductance valve 124. Thesystem further comprises a first processing station 128 and a secondprocessing station 132. The first processing station 128 has a first gasoutlet 136. The second processing station 132 has a second gas outlet140. A fifth variable conductance valve 144 is connected to the firstgas outlet 136. A sixth variable conductance valve 148 is connected tothe second gas outlet 140. A first mixing manifold 152 is connected tothe fifth variable conductance valve 144. A second mixing manifold 156is connected to the sixth variable conductance valve 148. A firstmanifold 160 is connected between the first variable conductance valve112 and the first mixing manifold 152. A second manifold 164 isconnected between the second variable conductance valve 116 and thesecond mixing manifold 156. A third manifold 168 is connected betweenthe third variable conductance valve 120 and the first mixing manifold152. A fourth manifold 172 is connected between the fourth variableconductance valve 124 and the second mixing manifold 156. In thisparagraph, the connections are fluid connections which allow a fluid topass from a first item to a second item. For example, since the firstmixing manifold 152 is connected to the fifth variable conductance valve144, fluid, such as a gas, is able to pass from the first mixingmanifold 152 to the fifth variable conductance valve 144. In addition,since fluid can pass from the first variable conductance valve 112 tothe first gas outlet 136 through the first manifold 160, the firstmixing manifold 152, and the fifth variable conductance valve 144 thefirst variable conductance valve 112 is connected to the first gasoutlet 136.

FIG. 2 is a schematic view of a process chamber which may be used in anembodiment for the first processing station 128. In one or moreembodiments, the first processing station 128 comprises the first gasoutlet 136 in the form of a distribution plate and a wafer support 208,within a chamber 249, enclosed by a chamber wall 252. Within the chamber249, a substrate 203 is positioned over the wafer support 208. An edgering 209 surrounds the wafer support 208. A support temperaturecontroller 250 is connected the wafer support 208. A radio frequency(RF) source 230 provides RF power to an upper electrode, which in thisembodiment is the first gas outlet 136. In an exemplary embodiment, 400kHz, 13.56 MHz, and optionally 2 MHz, 27 MHz power sources make up theRF source 230. In this embodiment, the wafer support 208 is grounded. Inthis embodiment, one generator is provided for each frequency. In otherembodiments, the generators may be in separate RF sources, or separateRF generators may be connected to different electrodes. For example, theupper electrode may have inner and outer electrodes connected todifferent RF sources. Other arrangements of RF sources and electrodesmay be used in other embodiments. A controller 235 is controllablyconnected to the RF source 230, an exhaust pump 220, and the gas source210. An example of such a chamber is the Striker™ Oxide systemmanufactured by Lam Research Corporation of Fremont, Calif.

FIG. 3 is a high level block diagram showing a computer system 300,which is suitable for implementing a controller 235 used in embodiments.The computer system may have many physical forms ranging from anintegrated circuit, a printed circuit board, and a small handheld deviceup to a huge super computer. The computer system 300 includes one ormore processors 302, and further can include an electronic displaydevice 304 (for displaying graphics, text, and other data), a mainmemory 306 (e.g., random access memory (RAM)), storage device 308 (e.g.,hard disk drive), removable storage device 310 (e.g., optical diskdrive), user interface devices 312 (e.g., keyboards, touch screens,keypads, mice or other pointing devices, etc.), and a communicationsinterface 314 (e.g., wireless network interface). The communicationsinterface 314 allows software and data to be transferred between thecomputer system 300 and external devices via a link. The system may alsoinclude a communications infrastructure 316 (e.g., a communications bus,cross-over bar, or network) to which the aforementioned devices/modulesare connected.

Information transferred via communications interface 314 may be in theform of signals such as electronic, electromagnetic, optical, or othersignals capable of being received by communications interface 314, via acommunication link that carries signals and may be implemented usingwire or cable, fiber optics, a phone line, a cellular phone link, aradio frequency link, and/or other communication channels. With such acommunications interface, it is contemplated that the one or moreprocessors 302 might receive information from a network, or might outputinformation to the network in the course of performing theabove-described method steps. Furthermore, method embodiments mayexecute solely upon the processors or may execute over a network such asthe Internet, in conjunction with remote processors that share a portionof the processing.

The term “non-transient computer readable medium” is used generally torefer to media such as main memory, secondary memory, removable storage,and storage devices, such as hard disks, flash memory, disk drivememory, CD-ROM, and other forms of persistent memory and shall not beconstrued to cover transitory subject matter, such as carrier waves orsignals. Examples of computer code include machine code, such asproduced by a compiler, and files containing higher level code that areexecuted by a computer using an interpreter. Computer readable media mayalso be computer code transmitted by a computer data signal embodied ina carrier wave and representing a sequence of instructions that areexecutable by a processor.

FIG. 4 is a high level flow chart of a method used in an embodiment. Aplurality of substrates 203 is processed in the first processing station128 and the second processing station 132 (step 404). The substrates 203may be test wafers, such as blank wafers or wafers with stacks and/ordevices on the wafers for testing. The processed substrates 203 aremeasured to measure and determine station to station uniformity (step408). The first, second, third, fourth, fifth, and sixth variableconductance valves 112, 116, 120, 124, 144, and 148 are adjusted tochange the resistance of flow to adjust flow rates to improve station tostation uniformity (step 412). If more tests are needed to check theresults of the changes (step 416) then the process goes back to step404. Otherwise, the first processing station 128 and the secondprocessing station 132 are used to process substrates 203 in production(step 420). The substrates 203 may be production wafers used forproducing devices instead of testing the stations.

In the example process chamber above, the first processing station 128and the second processing station 132 are used for atomic layerdeposition of silicon oxide (SiO₂). In the above example, the firstprocessing station 128 is in a separate processing chamber than thesecond processing station 132. In the above example and in other typesof substrate processing, station to station uniformity when differentstations share a common gas source, is not always achieved. Withoutbeing bound by theory, it is believed that differences between stationssuch as different resistances in the gas flow systems, differentvolumes, different powers, or different temperatures cause differencesin processing of wafers in different stations. It has been unexpectedlyfound that by changing the resistance of gas flow using the differentvariable conductance valves, station to station uniformity can beimproved even if the nonuniformity is being caused by differences in theprocessing chambers other than differences in the resistances in the gasflow systems.

In other embodiments, a different number of stations may share a commongas source. In some embodiments, more than one processing station may bein a single chamber. Other embodiments may have different numbers of gassources. For example, one embodiment may have a single gas source fortwo or more processing stations. Another example may have three or moregas sources for two or more processing stations.

In some embodiments, the variable conductance valves may be butterflyvalves designed to adjust resistance in the variable conductance valve.In other embodiments, a series of different sized orifices may be usedto adjust resistance to provide the variable conductance valve. In someembodiments, the variable conductance valve may be mechanicallyadjusted. In other embodiments, the variable conductance valve may beelectronically adjusted. Electronically adjusted variable conductancevalves may be adjusted by the controller 235. The processing ofsubstrates, measuring the processed substrates, adjusting the variableconductance valves by the controller 235, and then processing additionalsubstrates, provides a feedback loop. The first gas source 104 may havea mass flow controller. The second gas source 108 may have a mass flowcontroller. The variable conductance valves are separate from anddifferent from mass flow controllers, since mass flow controllers areset to provide a flow rate, whereas adjustable variable conductancevalves provide an adjustable flow resistance.

In another example, a single processing station may be connected to oneor more gas sources, with a variable conductance valve between thesingle processing station and the one or more gas sources. In thisexample, even though the single processing station does not share gassources with other single processing stations, the presence of avariable conductance valve may be used to improve station to stationuniformity. For a process, a recipe may be provided. The recipe may beused for multiple stations. If the above station has a different volumeor a heater is not correctly gauged, the provided recipe will have adifferent result than another station. It is believed that adjusting thevariable conductance valve may be used to compensate for differences,such as different volumes or temperatures. Such a compensation wouldallow the processing station to provide a more uniform result with otherprocessing stations for a given recipe.

In another embodiment, four processing stations may share a gas sourcein a single processing chamber. FIG. 5A is a cut away top schematic viewof a processing chamber 500 with four processing stations. Theprocessing chamber 500 has a chamber wall 504. FIG. 5B is a cut awayside view of the chamber. Within the chamber wall 504 are located foursubstrates 508 located at four processing stations within the processingchamber 500. Each processing station comprises a pedestal 512 forsupporting a substrate 508, a gas outlet 516 for providing gas to thesubstrate 508, and a manifold 520 connecting the gas outlet 516 to avariable conductance valve and a mixing manifold (not shown).

FIG. 6 is a schematic view of a gas delivery system 600 that may be usedfor the processing chamber 500 in FIG. 5 . In this example, the gasdelivery system 600 has a first gas source 604 and a second gas source608. The first gas source 604 is in fluid connection with four variableconductance valves 612, since in this example the first gas source 604is shared between four gas outlets 516 for four processing stations (notshown). The second gas source 608 is in fluid connection with fourvariable conductance valves 616. Each of the four gas outlets 516 isconnected through a manifold 520 to a variable conductance valve 620 anda mixing manifold 624, as shown. Each mixing manifold 624 is connectedthrough manifolds 628 to a variable conductance valve 612 in fluidconnection with the first gas source 604 and a manifold 632 to avariable conductance valve 616 in fluid connection with the second gassource 608.

This embodiment, allows the improvement of station to station uniformityfor four processing stations connected to the same gas sources. It hasbeen found that station to station nonuniformity in such systems is themost significant source of nonuniformity.

While this disclosure has been described in terms of several preferredembodiments, there are alterations, modifications, permutations, andvarious substitute equivalents, which fall within the scope of thisdisclosure. It should also be noted that there are many alternative waysof implementing the methods and apparatuses of the present disclosure.It is therefore intended that the following appended claims beinterpreted as including all such alterations, modifications,permutations, and various substitute equivalents as fall within the truespirit and scope of the present disclosure.

What is claimed is:
 1. A method of processing a plurality of stacks, ina processing system comprising first gas source, a first gas manifoldconnected to the first gas source, a second gas manifold connected tothe first gas source, a first processing station with a first gasoutlet, wherein the first gas outlet is connected to the first gasmanifold, a second processing station with a second gas outlet, whereinthe second gas outlet is connected to the second gas manifold, a firstvariable conductance valve between the first gas source and the firstgas outlet along the first gas manifold, a second variable conductancevalve between the first gas source and the second gas outlet along thesecond gas manifold, a first mixing manifold between the first variableconductance valve and the first gas outlet, along the first gasmanifold, a second mixing manifold between the second variableconductance valve and the second gas outlet, along the second gasmanifold, a second gas source, a third gas manifold connected betweenthe second gas source and the first mixing manifold, a fourth gasmanifold connected between the second gas source and the second mixingmanifold, a third variable conductance valve connected between secondgas source and the first mixing manifold along the third gas manifold, afourth variable conductance valve connected between the second gassource and the second mixing manifold along the fourth gas manifold, afifth variable conductance valve between the first mixing manifold andthe first gas outlet, and a sixth variable conductance valve between thesecond mixing manifold and the second gas outlet, the method comprisingadjusting the first variable conductance valve, the second variableconductance valve, the third variable conductance valve, the fourthvariable conductance valve, the fifth variable conductance valve, andthe sixth variable conductance valve to provide improved uniformitybetween the first processing station and the second processing station.2. The method, as recited in claim 1, further comprising: processingsubstrates of test wafers in the first processing station and the secondprocessing station; measuring the substrates; and determining station tostation uniformity between the first processing station and the secondprocessing station.
 3. The method, as recited in claim 2, furthercomprising processing substrates of production wafers in the firstprocessing station and the second processing station.